CA1304784C - Optical communication apparatus for motor vehicle - Google Patents

Abstract

Abstract of the Disclosure An optical communication apparatus for motor vehicles comprising: using a light emitting diode of a rear combination lamp, marker lamp or the like as a light emitting element;
providing a light receiving element near at the light emitting element; and connecting a transmitter to the light emitting element and a receiver to the light receiving element.

Description

- ~3~4~1 SPECIFICATIO~
O~tical Communication A~paratus for Motor Vehicle Background to the Invention (Field of the Invention) The present invention relates to an optical communication apparatus mounted on four-wheel motor vehicles for optical communication among them.
(Prior Art) If a plurality of persons move from one location to another location, a plurality of motor vehicles are used. In such a case, communication among them may be required sometimes duriny such a trip, which communication should be kept secret to third parties.
If a radio communication is used among motor vehicles, there is a risk of leaking out the content of communication to third parties, posiny a problem of leakage of secret.
Summary of the Invention It ls therefore an object of the present invention to ~rovide an optical communication apuaratus for motor vehicles capable of kee~ing secret during communication among theln.
According to an aspect of the present invention, an optical communication a~aratus for motor vehicles comprises using a light emittiny diode of a rear combination lamp, marker lamp or the like as a light emitting element, providing a light receiviny element near at the liyht emitting element, and connectillg a transmitter to the light emitting element and a receiver to the light receiving element.
Brief Description of the Drawings ` 1304784 The above and other objects and advantages of the present invention will be described in more detail in the following, by way of example, reference being made to the accompanying drawinys, in which:
Fig.1 is a block diagram showing an embodiment of an optical communication apparatus for a motor vehicle accordiny to the present invention;
Fig.2 is a side elevational view illustrating how optical communication is performed among motor vehicles; and Figs.3 and 4 show the mounting condition of the light emitting and receiving elements of the embodiment.
Detailed Description of the Preferred Embodiment An embodiment of this invention will be described in detail with reference to the accompanying drawings.
Figs.1 to 4 show an embodiment of the optical communication apparatus for a motor vehicle according to the present invention. Referring to the figures, reference numeral 1 represents a ~icrophone, 2 an amplifier for amplifying a voice or audio siynal, 3 an FM modulator for FM modulating the voice signal, 4 a power amplifier, and 5A and 5B a light emitting element driven by an output from the amplifier 4. If a rear combination lamp (refer to Fig.3) and front marker lamp (refer to Fig.4) are constructed of light emitting diodes (LEDsj, then LEDs are used as the light emitting elements.
6A and 6B represent light receiving elements such as photodiodes, 7 an amplifier for amplifying received siynal, 8 ~304784 an FM demodulator for FM demodulating an output from the amplifier, 9 a voice or audio signal amplifier for amplifyiny a voice signal, and 10 a loudspeaker. The light receiving elements 6A and 6B are mounted near at the rear combination lamp (shown in Fig.3) and marker lamp (shown in Fig.4).
The rear, and front light emitting elements 5A and 5B, and the light receiving elements 6A and 6B are interchanyeably switched by using a switch 11, respectively.
In operation, for example, for communication between motor vehicles A and B as shown in Fig.2, light pulses of a carrier frequency fa modulated by voice is emitted out from the light emitting element 5B of the motor vehicle ~ to the motor vehicle B. The light pulses are received by the liyht receiving element mounted at the front of the motor vehicle B, amplified, FM modulated, audio-amplified, and supplied to the loudspeaker 10 to yenerate voices.
On the contrary, light pulses of a carrier frequency fb are emitted out from the motor vehicle s to the motor vehicle A. The light pulses are received by the light receiving element mounted at the rear of the motor vehicle A, amplified, FM demodulated, audio-amplified, and supplied to the loudspeaker 10 to yenerate voices.
Unless optical communication is not performed in full duplex manner, a same carrier frequel1cy can be used in sending and receiving light pulses.
As appreciated from the foreyoing description of the present invention, although a service area is limited because of optical communication, cross talk can be reduced. Further, as the light emitting element, the LEDs of the rear combination lamp and marker lamp can be used so that no additional light emitting element for such particular function is not used, resulting in low cost. In addition, by using different carrier frequencies in sending and receiving light yulses, optical communication can be realized simultaneously among motor vehicles.
Although the present invention has been described in connection with the preferred embodiment thereof with reference to the accompanying drawings, it will be apparent to those skilled in the art that various changes and modifications of the present invention are possible within the scope of the following claim.

Claims (15)

1. An optical communication apparatus for vehicles, comprising:
at least one of a rear combination lamp and a marker lamp on a first vehicle, said at least one of a rear combination lamp and marker lamp including a light emitting means for emitting a visually observable light signal;
a source of optical communication signals, including said light emitting means of said at least one of a rear combination lamp and a marker lamp of said first vehicle for use also for generating optical communications signals;
light receiving means on said first vehicle and located in the vicinity of said light emitting means for receiving from a light source in a second vehicle optical communications signals related to an original signal;
transmitting means on said first vehicle and coupled to said light emitting means for causing said light emitting means to also emit said optical communications signals; and receiver means coupled to said light receiving means for converting said received optical communications signals into substantially said original signal.

2. The optical communication apparatus of claim 1, wherein said light receiving means receives optical communications signals from said second vehicle.

3. The optical communication apparatus of claim 1, wherein said light receiving means on said first vehicle is located near said light emitting means of said first vehicles.

4. The optical communication apparatus of claim 1, wherein said light receiving means on said first vehicle is located adjacent to said light emitting means of said first vehicle.

5. The optical communication apparatus of claim 1, wherein said transmitting means includes:
a microphone; and FM modulator means for receiving input signals from said microphone and coupled to said light emitting means for causing said light emitting means to generate said optical communications signals responsive to an FM
modulated output of said FM modulator means.

6. The optical communication apparatus of claim 5, wherein said receiver means includes:
FM demodulator means coupled to said light receiving means for FM demodulating optical communications signals received by said light receiving means; and audio output means coupled to said FM demodulator means for producing an audio output in accordance within FM demodulated output of said FM demodulator means.

7. The optical communication apparatus of claim 5, wherein said receiver means includes:
FM demodulator means coupled to said light receiving means for FM demodulating optical communications signals received by said light receiving means; and audio output means coupled to said FM demodulator means for producing an audio output in accordance with an FM demodulated output of said FM demodulator means.

8. The optical communication apparatus of claim 7, wherein said FM demodulator means and said FM modulator means operate with different carrier frequencies.

9. The optical communication apparatus of claim 7, wherein said FM demodulator means of different vehicles have different carrier frequencies.

10. The optical communication apparatus of claim 1, wherein said light emitting means comprises at least one light emitting diode (LED) serving for emitting said visually observable light signal for said at least one of said rear combination lamp and marker lamp and for emitting said optical communications signals.

11. The optical communication apparatus of claim 1, wherein said light receiving means comprises a plurality of closely adjacent photodiodes.

12. A method of optical communication between vehicles, comprising:
providing at least one of a rear combination lamp and a marker lamp on a first vehicle, said at least one of a rear combination lamp and marker lamp including a light emitting means for emitting a visually observable light signal;
providing a source of optical communications signals including said light emitting means of said at least one of a rear combination lamp and marker lamp, for use also for generating optical communication signals;
generating an electrical communications signal containing original information to be transmitted from said first vehicle to a second vehicle;
emitting an optical communications signal corresponding to said electrical communications signals by means of said light emitting means;
receiving said optical communications signals at said second vehicle;
converting said received optical communications signals at said second vehicle into a signal representative substantially of said original information;
said second vehicle including light receiving means located in the vicinity of a light emitting means of said at least one of a rear combination lamp and marker lamp of said second vehicle.

13. The method of claim 12, wherein said optical communications signals emitted from said first vehicle has a carrier frequency which is different from an optical communications signals emitted from said second vehicle.

14. The optical communication method of claim 12, wherein said light emitting elements comprise at least one light emitting diode (LED) serving as both a light source of at least one of said rear combination lamp and marker lamp, and for generating said optical communications signals.

15. The optical communication method of claim 12, wherein the receiving step comprises providing a plurality of photodiodes closely adjacent to each other.